Plug bridge comprising a hollow pin

ABSTRACT

The invention relates to a plug bridge comprising a base plate and a hollow pin that penetrates said base plate. The hollow space of the hollow pin, which is open at the socket end, is provided with a seal in order to prevent any base plate material from penetrating into it during the manufacture of the plug bridge.

The present invention relates to the subject of the pre-characterizingclause. Thus, the present invention relates to plug bridges.

A plug bridge is a component of a power plug, in which is establishedthe connection between the contacts to be inserted into a wall socket,i.e., the ground connection and/or the plug pins on the one side, andthe insulated strands of a power cable on the other. The plug bridgeencloses the plug pins in a geometrical orientation as prescribed by therelevant electrical code, and—on its strand connection end—has a simpleconnection device, such as a crimp wing, to be crimped with the leads,solder tails, lead-in funnels for crimping, bolt connections, etc.

There already exist plug bridge arrangements used to connect with powercables in which hollow space is used, i.e., plug pins that are stampedand cut from metal sheet and/or bent and/or their insides comprisehollow space. This is advantageous as such, because hollow space can beproduced with less material and in a shorter amount of time than ittakes to manufacture plug pins whose form must be turned from full,non-hollow material. An additional advantage of the hollow design isthat it weighs less and is consequently easier to handle, transport,etc.

However, the advantage of hollow pins is more than outweighed byproblems inherent to their design. In addition, it is not possible touse hollow pin contacts in waterproof plugs. According to current safetyregulations, synthetic material of the plug bridge must not penetrateinto the hollow space of the plug pin. During the process of spraycoating the hollow-pin, the plug contacts with a synthetic material thatforms the plug bridge, and since this danger exists, the current stateof the art requires that the hollow pins be built into the plug bridgebase plate after it has been manufactured. This means that water ormoisture in the hollow space of the pin can travel up to the strands ofthe power cable and cause the contacts to corrode, which impairs thelong-term stability of the plug and thus prevents the plug from beingused in outdoor applications, in humid spaces, and similar environments.

The task of the present invention is to provide a technical novelty forindustrial use.

This task is resolved in an independent form. Preferred furtherdevelopments are claimed in dependent claims.

As the first basic concept, the present invention proposes a plug bridgecomprising a base plate and a hollow pin that penetrates this baseplate, wherein the hollow space of the hollow pin, which is open at thesocket end, is provided with a seal in order to prevent any base platematerial from penetrating into it during the manufacture of the plugbridge.

Thus, the first essential aspect of the present invention consists inthe fact that a seal introduced into the hollow pin during itsmanufacture prevents the base plate material from penetrating into thehollow space—which is open at the socket end—during the manufacture ofthe plug bridge. The provision of the seal during the manufacture of thehollow pin does not pose any problems, and allows for a fastmanufacturing process, so that the seal increases the manufacturingcosts by only a small amount. However, this miniscule cost increase ismore than outweighed by the beneficial fact that the hollow pin can befully enveloped during the molding of the base plate.

Therefore, the base plate is preferably molded and/or injection-molded.This can be done in a conventional form, while leaving a lead-in funnelfor the lead end to be connected through a crimp pipe, and anotherlead-in funnel for the lead end of the ground connection, etc. In thisconnection we wish to point out that a plug bridge according to thisinvention already exists, if only a single hollow pin of the describedtype is provided in the plug bridge; in typical 220V safety plugs, bothhollow pins are usually fitted with the aforementioned seal. In theseplugs, round hollow pins are fitted with a seal; however, we must pointout that such seals can also be used for angular pins.

The hollow pins can be manufactured by bending up stamped and/orembossed metal sheets, in which case there is then a gap in the areaclose to the plug, into which moisture or similar element can penetrate.However, this moisture cannot penetrate all the way into the inside ofthe plug itself, because the hollow pin is fully enveloped by the baseplate material and, after the base plate is manufactured, this materialensures that the hollow pin is hermetically sealed.

In a preferred form, the seal is formed by a little plate built into thehollow space. Since this little plate has contact with the entire insidespace of the hollow pin, it is even more stabilized during thespray-molding process. Thus, another special advantage of the inventionis an increase in the form stability and, therefore, in the safety ofits operation.

The little plate can be fixed by a circumferential knurl and/or anembossed edge. Alternatively, clinched tabs can be used to fix thesealing plate.

In an especially preferred variant, the seal, i.e., the little plate, ismade of the same material as the hollow pin. This is advantageous,because the base plate material is usually molded while hot, and theselection of the same material prevents different expansion coefficientsfrom destroying the seal during the manufacturing of the base plate.

It is further preferred that the seal is fixed close to the surface ofthe base plate on the side of the plug, and also that lateral aperturesare arranged in the hollow pin's wall. These apertures are locatedcloser to the connection with the power cable, but are still in the areaof the base plate, so that, during the manufacturing of the base plate,the base plate material can penetrate into the hollow pin as far as theseal and, after solidifying, will prevent the pin from twisting.Alternatively and/or in addition, the protection against twisting can beenhanced by the design of the crimp connection.

In the following text, the invention will be explained using an exampleand drawings.

FIG. 1 shows a sectional view through a plug bridge with hollow pins asdesigned by the invention;

FIG. 2 shows a sectional view at a different plane;

FIG. 3 shows an example of a band with the hollow pins as designed bythe invention;

FIG. 4 shows a perspective view of a plug bridge as designed by theinvention;

FIG. 5 shows another exemplary design of a plug pin.

As shown in FIG. 1, a plug bridge 1—generally denoted with 1—comprises abase plate 2 and hollow pins 3 that penetrate said base plate. Thehollow space of the hollow pin, which is open—through a slot 3 a (SeeFIG. 3)—at the socket end, is provided with a seal 4 in order to preventany base plate material from penetrating into it during the manufactureof the plug bridge.

The plug bridge base plate 2 is made of a fiber-reinforced,non-conductive synthetic material and generally has a U-shapecross-section. The U-shaped branches 2 a that extend towards the gripbody of the plug can be fitted with attachment elements for a groundconnection clip (not shown). Lead-in funnels 2 b can be provided in thebase plate above the connection points and between the ground contactclip and/or the connection ends of the hollow pins 3 on the one side,and the power cable strands on the other side. These lead-in funnels canbe molded as one piece with the base plate or can be inserted into it. Ahollow space 2 c can be provided to contain the ground connection pin ora similar element in order to connect with properly standardized plugs.

The hollow pin 3 is made of a metal sheet band. During the manufacturingprocess, the metal sheet band contains a whole number of hollow pins, asis shown in FIG. 3 (2 hollow pins in top view). The shown hollow pin 3 ahas a wall 3 b made of metal sheet material that comprises apertures 3d, which are close to the connection point 3 c for the connection of thepower cable, and are located above the seal 4. These apertures aresufficiently large for the base plate material when hot, and of aviscosity sufficient to penetrate, during the manufacturing of the plugbridge, into the space 3 e that is visible in the cross-section view ofa hollow pin in FIG. 3. In the area of the seal 4, the wall 3 b of thehollow pin 3 is curled along its entire circumference as is made visibleby the recess 3 f. We wish to point out that the dimensions shown in thedrawings do not limit the patent protection, but are to be taken only asan example. The seal 4 is made of the same material as the electricallyconductive hollow pin.

The plug bridge is manufactured as follows:

First, the hollow pin is made of a sheet metal band, and the littleround plates 4 are built in during the stamping and folding process.

The thus obtained metal sheet band (with completed hollow pins) is thendivided into individual hollow pins, and these are spray-coated with thehot material of the base plate in the area of the cover 4 up to the edge3 g on its side towards the power cable connection point 3 c. The baseplate material fully encloses the hollow pin, penetrates into the space3 e, and overlaps it. Due to the fact that the sealing plate 4 is sealedby the recess 3 f, the hot base plate material cannot penetrate thehollow space past the seal 4 during the manufacturing process.

After the base plate hardens and the ground connection spring bracket ismounted, a power cable can be connected, which is done in the shownexample design using crimping at the crimp wings 3 c 1 on the side 3 c.In other designs, this is achieved by soldering, bolting, or similarfastening procedures. Afterwards, the grip body is spray-coated with PVCor a similar material so that the contact zone between the strandconnection end 3 c and the power cable end is completely enveloped andhermetically sealed from the outside environment with no danger thatmoisture will penetrate past the sealing plate and into the inside spaceof the grip body. In addition, the base plate material firmly restsagainst the seal and thus creates a sealed base plate surface that isnearly absolutely vapor-tight. A plug that comprises a hollow pin and/ora plug bridge as designed by the invention and/or which has beenfabricated according to the invented method, is ideally suited for usein a humid environment, outdoors, etc., although hollow pins are usedinstead of pins turned out of full material.

According to FIG. 5, the seal in the form of a cover plate is providedon the upper end of the hollow pin. The cover plate rests on an edgezone slightly curled, pressed inside, or embossed, and is then fixedfrom above by tabs. This manufacturing technique is simple andeliminates weight.

1. Plug bridge comprising a base plate and a hollow pin that penetrates said base plate, characterized in that the hollow space of the hollow pin, which is open at the socket end, is provided with a seal in order to prevent any base plate material from penetrating into it during the manufacture of the plug bridge.
 2. Plug bridge according to claim 1, characterized in that the base plate is molded and/or injection-molded.
 3. Plug bridge according to claim 2, characterized in that the hollow pin is fully enveloped by spray molding in the area of the base plate level.
 4. Plug bridge according to claim 1, characterized in that the hollow pin is folded from a stamped and/or embossed piece of metal sheet.
 5. Plug bridge according to claim 1, characterized in that the seal is designed as a small plate built into the hollow space.
 6. Plug bridge according to claim 1, characterized in that the small plate is fixed by means of a circumferential embossed edge, and particularly between two such edges.
 7. Plug bridge according to claim 1, characterized in that the small plate is made of the same material as the hollow pin.
 8. Plug bridge according to claim 1, characterized in that, between the seal and the part of the hollow pin that protrudes over the base plate, at least one lateral aperture is provided in the wall of the hollow pin in order to facilitate the penetration of the base plate material up to the seal, so as to enhance its protection against twisting.
 9. Plug bridge according to claim 1, characterized in that the seal is provided at the end of the hollow pin that is adjacent to the crimp connection.
 10. Hollow pin for a plug bridge according to claim
 1. 11. Plug bridge according to claim 2, characterized in that the hollow pin is folded from a stamped and/or embossed piece of metal sheet.
 12. Plug bridge according to claim 3, characterized in that the hollow pin is folded from a stamped and/or embossed piece of metal sheet.
 13. Plug bridge according to claim 2, characterized in that the seal is designed as a small plate built into the hollow space.
 14. Plug bridge according to claim 3, characterized in that the seal is designed as a small plate built into the hollow space.
 15. Plug bridge according to claim 4, characterized in that the seal is designed as a small plate built into the hollow space.
 16. Plug bridge according to claim 2, characterized in that the small plate is fixed by means of a circumferential embossed edge, and particularly between two such edges.
 17. Plug bridge according to claim 3, characterized in that the small plate is fixed by means of a circumferential embossed edge, and particularly between two such edges.
 18. Plug bridge according to claim 4, characterized in that the small plate is fixed by means of a circumferential embossed edge, and particularly between two such edges.
 19. Plug bridge according to claim 5, characterized in that the small plate is fixed by means of a circumferential embossed edge, and particularly between two such edges.
 20. Plug bridge according to claim 2, characterized in that the small plate is made of the same material as the hollow pin. 